Grass blocks do not regenerate as grass, they just stay dirt.  Does not matter how many in-game days, they just stay dirt.  Dirt blocks, when placed next to grass blocks do not become grass blocks.  They just stay dirt.  When animals graze the grass blocks the blocks turn to dirt and do not go back to grass. 

It does not matter what texture pack I have used, from Vanilla to Zigzag, it just stays dirt.  Also, the game mode, whether survival or creative, does not seem to effect it either.  I was hoping after this last bug fix it would be fixed because it seems like such an obvious thing that someone would have reported it, but apparently not.

I have started different worlds trying out different scenarios and it is still dirt.  This is really bothering me.  Attached it screenshot of latest world.  Seriously, after several days you end up with dirt blocks only all around your house and the animals leave.